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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (June 22, 2020) is 1405 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 8321 (Obsoleted by RFC 9341) Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6MAN Working Group G. Fioccola 3 Internet-Draft T. Zhou 4 Intended status: Standards Track Huawei 5 Expires: December 24, 2020 M. Cociglio 6 Telecom Italia 7 F. Qin 8 China Mobile 9 R. Pang 10 China Unicom 11 June 22, 2020 13 IPv6 Application of the Alternate Marking Method 14 draft-ietf-6man-ipv6-alt-mark-01 16 Abstract 18 This document describes how the Alternate Marking Method can be used 19 as the passive performance measurement tool in an IPv6 domain and 20 reports implementation considerations. It proposes how to define a 21 new Extension Header Option to encode alternate marking technique and 22 both Hop-by-Hop Options Header and Destination Options Header are 23 considered. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 29 document are to be interpreted as described in BCP 14 [RFC2119] 30 [RFC8174] when, and only when, they appear in all capitals, as shown 31 here. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at https://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on December 24, 2020. 50 Copyright Notice 52 Copyright (c) 2020 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (https://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. Alternate Marking application to IPv6 . . . . . . . . . . . . 3 69 3. Definition of the AltMark Option . . . . . . . . . . . . . . 4 70 3.1. Data Fields Format . . . . . . . . . . . . . . . . . . . 4 71 4. Use of the AltMark Option . . . . . . . . . . . . . . . . . . 5 72 5. Alternate Marking Method Operation . . . . . . . . . . . . . 7 73 5.1. Packet Loss Measurement . . . . . . . . . . . . . . . . . 7 74 5.2. Packet Delay Measurement . . . . . . . . . . . . . . . . 8 75 5.3. Flow Monitoring Identification . . . . . . . . . . . . . 9 76 5.3.1. Uniqueness of FlowMonID . . . . . . . . . . . . . . . 10 77 5.4. Multipoint and Clustered Alternate Marking . . . . . . . 10 78 5.5. Data Collection and Calculation . . . . . . . . . . . . . 11 79 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 80 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 81 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 82 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 83 9.1. Normative References . . . . . . . . . . . . . . . . . . 13 84 9.2. Informative References . . . . . . . . . . . . . . . . . 13 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 87 1. Introduction 89 [RFC8321] and [I-D.ietf-ippm-multipoint-alt-mark] describe a passive 90 performance measurement method, which can be used to measure packet 91 loss, latency and jitter on live traffic. Since this method is based 92 on marking consecutive batches of packets, the method is often 93 referred as Alternate Marking Method. 95 The Alternate Marking Method has become mature to be implemented and 96 encoded in the IPv6 protocol and this document defines how it can be 97 used to measure packet loss and delay metrics in IPv6. 99 The format of the IPv6 addresses is defined in [RFC4291] while 100 [RFC8200] defines the IPv6 Header, including a 20-bit Flow Label and 101 the IPv6 Extension Headers. The Segment Routing Header (SRH) is 102 defined in [RFC8754]. 104 [I-D.fioccola-v6ops-ipv6-alt-mark] reported a summary on the possible 105 implementation options for the application of the Alternate Marking 106 Method in an IPv6 domain. This document, starting from the outcome 107 of [I-D.fioccola-v6ops-ipv6-alt-mark], introduces a new TLV that can 108 be encoded in the Options Headers (both Hop-by-Hop or Destination) 109 for the purpose of the Alternate Marking Method application in an 110 IPv6 domain. The case of SRH ([RFC8754]) is also discussed, anyway 111 this is valid for all the types of Routing Header (RH). 113 2. Alternate Marking application to IPv6 115 The Alternate Marking Method requires a marking field. As mentioned, 116 several alternatives have been analysed in 117 [I-D.fioccola-v6ops-ipv6-alt-mark] such as IPv6 Extension Headers, 118 IPv6 Address and Flow Label. 120 In consequence to the previous document and to the discussion within 121 the community, it is possible to state that the only correct and 122 robust choice that can actually be standardized would be the use of a 123 new TLV to be encoded in the Options Header (Hop-by-Hop or 124 Destination Option). 126 This approach is compliant with [RFC8200] indeed the Alternate 127 Marking application to IPv6 involves the following operations: 129 o The source node is the only one that writes the Option Header to 130 mark alternately the flow (for both Hop-by-Hop and Destination 131 Option). 133 o In case of Hop-by-Hop Option Header carrying Alternate Marking 134 bits, it is not inserted or deleted, but can be read by any node 135 along the path. The intermediate nodes may be configured to 136 support this Option or not. Anyway this does not impact the 137 traffic since the measurement can be done only for the nodes 138 configured to read the Option. 140 o In case of Destination Option Header carrying Alternate Marking 141 bits, it is not processed, inserted, or deleted by any node along 142 the path until the packet reaches the destination node. Note 143 that, if there is also a Routing Header (RH), any visited 144 destination in the route list can process the Option Header. 146 Hop-by-Hop Option Header is also useful to signal to routers on the 147 path to process the Alternate Marking, anyway it is to be expected 148 that some routers cannot process it unless explicitly configured. 150 The optimization of both implementation and scaling of the Alternate 151 Marking Method is also considered and a way to identify flows is 152 required. The Flow Monitoring Identification field (FlowMonID), as 153 introduced in the next sections, goes in this direction and it is 154 used to identify a monitored flow. 156 Note that the FlowMonID is different from the Flow Label field of the 157 IPv6 Header ([RFC8200]). Flow Label is used for application service, 158 like load-balancing/equal cost multi-path (LB/ECMP) and QoS. 159 Instead, FlowMonID is only used to identify the monitored flow. The 160 reuse of flow label field for identifying monitored flows is not 161 considered since it may change the application intent and forwarding 162 behaviour. Furthermore the flow label may be changed en route and 163 this may also violate the measurement task. Those reasons make the 164 definition of the FlowMonID necessary for IPv6. Flow Label and 165 FlowMonID within the same packet have different scope, identify 166 different flows, and associate different uses. 168 An important point that will also be discussed in this document is 169 the the uniqueness of the FlowMonID and how to allow disambiguation 170 of the FlowMonID in case of collision. [RFC6437] states that the 171 Flow Label cannot be considered alone to avoid ambiguity since it 172 could be accidentally or intentionally changed en route for 173 compelling operational security reasons and this could also happen to 174 the IP addresses that can change due to NAT. But the Alternate 175 Marking is usually applied in a controlled domain, which would not 176 have NAT and there is no security issue that would necessitate 177 rewriting Flow Labels. So, for the purposes of this document, both 178 IP addresses and Flow Label should not change in flight and, in some 179 cases, they could be considered together with the FlowMonID for 180 disambiguation. 182 3. Definition of the AltMark Option 184 The desired choice is to define a new TLV for the Options Extension 185 Headers, carrying the data fields dedicated to the alternate marking 186 method. 188 3.1. Data Fields Format 190 The following figure shows the data fields format for enhanced 191 alternate marking TLV. This AltMark data is expected to be 192 encapsulated in the IPv6 Options Headers (Hop-by-Hop or Destination 193 Option). 195 0 1 2 3 196 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | Option Type | Opt Data Len | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | FlowMonID |L|D| Reserved | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 where: 205 o Option Type: 8 bit identifier of the type of Option that needs to 206 be allocated. Unrecognised Types MUST be ignored on receipt. For 207 Hop-by-Hop Options Header or Destination Options Header, [RFC8200] 208 defines how to encode the three high-order bits of the Option Type 209 field. The two high-order bits specify the action that must be 210 taken if the processing IPv6 node does not recognize the Option 211 Type; for AltMark these two bits MUST be set to 00 (skip over this 212 Option and continue processing the header). The third-highest- 213 order bit specifies whether or not the Option Data can change en 214 route to the packet's final destination; for AltMark the value of 215 this bit MUST be set to 0 (Option Data does not change en route). 217 o Opt Data Len: The length of the Option Data Fields of this Option 218 in bytes. 220 o FlowMonID: 20 bits unsigned integer. The FlowMon identifier is 221 described hereinafter. 223 o L: Loss flag for Packet Loss Measurement as described hereinafter; 225 o D: Delay flag for Single Packet Delay Measurement as described 226 hereinafter; 228 o Reserved: is reserved for future use. These bits MUST be set to 229 zero on transmission and ignored on receipt. 231 4. Use of the AltMark Option 233 The AltMark Option is the best way to implement the Alternate Marking 234 method and can be carried by the Hop-by-Hop Options header and the 235 Destination Options header. In case of Destination Option, it is 236 processed only by the source and destination nodes: the source node 237 inserts and the destination node removes it. While, in case of Hop- 238 by-Hop Option, it may be examined by any node along the path, if 239 explicitly configured to do so. In this way an unrecognized Hop-by- 240 Hop Option may be just ignored without impacting the traffic. 242 So it is important to highlight that the Option Layout can be used 243 both as Destination Option and as Hop-by-Hop Option depending on the 244 Use Cases and it is based on the chosen type of performance 245 measurement. In general, it is needed to perform both end to end and 246 hop by hop measurements, and the alternate marking methodology 247 allows, by definition, both performance measurements. Anyway, in 248 many cases the end-to-end measurement is not enough and it is 249 required also the hop-by-hop measurement, so the most complete choice 250 is the Hop-by-Hop Options Header. 252 IPv6, as specified in [RFC8200], allows nodes to optionally process 253 Hop-by-Hop headers. Specifically the Hop-by-Hop Options header is 254 not inserted or deleted, but may be examined or processed by any node 255 along a packet's delivery path, until the packet reaches the node (or 256 each of the set of nodes, in the case of multicast) identified in the 257 Destination Address field of the IPv6 header. Also, it is expected 258 that nodes along a packet's delivery path only examine and process 259 the Hop-by-Hop Options header if explicitly configured to do so. 261 The Hop-by-Hop Option defined in this document is designed to take 262 advantage of the property of how Hop-by-Hop options are processed. 263 Nodes that do not support this Option SHOULD ignore them. This can 264 mean that, in this case, the performance measurement does not account 265 for all links and nodes along a path. 267 Another application that can be mentioned is the presence of a 268 Routing Header, in particular it is possible to consider SRv6. SRv6 269 leverages the Segment Routing header which consists of a new type of 270 routing header. Like any other use case of IPv6, Hop-by-Hop and 271 Destination Options are useable when SRv6 header is present. Because 272 SRv6 is a routing header, Destination Options before the routing 273 header are processed by each destination in the route list. 275 In summary, it is possible to list the alternative possibilities: 277 o Destination Option => measurement only by node in Destination 278 Address. 280 o Hop-by-Hop Option => every router on the path with feature 281 enabled. 283 o Destination Option + SRH => every node that is an identity in the 284 SR path. 286 In general, Hop-by-Hop and Destination Options are the most suitable 287 ways to implement Alternate Marking. 289 It is worth mentioning that new Hop-by-Hop Options are not strongly 290 recommended in [RFC7045] and [RFC8200], unless there is a clear 291 justification to standardize it, because nodes may be configured to 292 ignore the Options Header, drop or assign packets containing an 293 Options Header to a slow processing path. In case of the AltMark 294 data fields described in this document, the motivation to standardize 295 a new Hop-by-Hop Option is that it is needed for OAM. An 296 intermediate node can read it or not but this does not affect the 297 packet behavior. The source node is the only one that writes the 298 Hop-by-Hop Option to mark alternately the flow, so, the performance 299 measurement can be done for those nodes configured to read this 300 Option, while the others are simply not considered for the metrics. 302 In addition to the previous alternatives, for legacy network it is 303 possible to mention a non-conventional application of the Destination 304 Option for the hop by hop usage. [RFC8200] defines that the nodes 305 along a path examine and process the Hop-by-Hop Options header only 306 if Hop-by-Hop processing is explicitly configured. On the other 307 hand, using the Destination Option for hop by hop action would cause 308 worse performance than Hop-by-Hop. The only motivation for the hop 309 by hop usage of Destination Options can be for compatibility reasons 310 but in general it is not recommended. 312 5. Alternate Marking Method Operation 314 This section describes how the method operates. [RFC8321] introduces 315 several alternatives but in this section the most applicable methods 316 are reported and a new fied is introduced to facilitate the 317 deployment and improve the scalability. 319 5.1. Packet Loss Measurement 321 The measurement of the packet loss is really straightforward. The 322 packets of the flow are grouped into batches, and all the packets 323 within a batch are marked by setting the L bit (Loss flag) to a same 324 value. The source node can switch the value of the L bit between 0 325 and 1 after a fixed number of packets or according to a fixed timer, 326 and this depends on the implementation. By counting the number of 327 packets in each batch and comparing the values measured by different 328 network nodes along the path, it is possible to measure the packet 329 loss occurred in any single batch between any two nodes. Each batch 330 represents a measurable entity unambiguously recognizable by all 331 network nodes along the path. 333 It is important to mention that for the application of this method 334 there are two elements to consider: the clock error between network 335 nodes and the network delay. These can create offsets between the 336 batches and out-of-order of the packets. The consequence is that it 337 is necessary to define a waiting interval where to get stable 338 counters and to avoid these issues. In addition this implies that 339 the length of the batches MUST be chosen large enough so that it is 340 not affected by those factors. 342 L bit=1 ----------+ +-----------+ +---------- 343 | | | | 344 L bit=0 +-----------+ +-----------+ 345 Batch n ... Batch 3 Batch 2 Batch 1 346 <---------> <---------> <---------> <---------> <---------> 348 Traffic Flow 349 ===========================================================> 350 L bit ...1111111111 0000000000 11111111111 00000000000 111111111... 351 ===========================================================> 353 Figure 1: Packet Loss Measurement and Single-Marking Methodology 354 using L bit 356 5.2. Packet Delay Measurement 358 The same principle used to measure packet loss can be applied also to 359 one-way delay measurement. Delay metrics MAY be calculated using the 360 two possibilities: 362 1. Single-Marking Methodology: This approach uses only the L bit to 363 calculate both packet loss and delay. In this case, the D flag 364 MUST be set to zero on transmit and ignored by the monitoring 365 points. The alternation of the values of the L bit can be used 366 as a time reference to calculate the delay. Whenever the L bit 367 changes and a new batch starts, a network node can store the 368 timestamp of the first packet of the new batch, that timestamp 369 can be compared with the timestamp of the first packet of the 370 same batch on a second node to compute packet delay. Anyway this 371 measurement is accurate only if no packet loss occurs and if 372 there is no packet reordering at the edges of the batches. A 373 different approach can also be considered and it is based on the 374 concept of the mean delay. The mean delay for each batch is 375 calculated by considering the average arrival time of the packets 376 for the relative batch. There are limitations also in this case 377 indeed, each node needs to collect all the timestamps and 378 calculate the average timestamp for each batch. In addition the 379 information is limited to a mean value. 381 2. Double-Marking Methodology: This approach is more complete and 382 uses the L bit only to calculate packet loss and the D bit (Delay 383 flag) is fully dedicated to delay measurements. The idea is to 384 use the first marking with the L bit to create the alternate flow 385 and, within the batches identified by the L bit, a second marking 386 is used to select the packets for measuring delay. The D bit 387 creates a new set of marked packets that are fully identified 388 over the network, so that a network node can store the timestamps 389 of these packets; these timestamps can be compared with the 390 timestamps of the same packets on a second node to compute packet 391 delay values for each packet. The most efficient and robust mode 392 is to select a single double-marked packet for each batch, in 393 this way there is no time gap to consider between the double- 394 marked packets to avoid their reorder. If a double-marked packet 395 is lost, the delay measurement for the considered batch is simply 396 discarded, but this is not a big problem because it is easy to 397 recognize the problematic batch and skip the measurement just for 398 that one. So in order to have more information about the delay 399 and to overcome out-of-order issues this method is preferred. 401 L bit=1 ----------+ +-----------+ +---------- 402 | | | | 403 L bit=0 +-----------+ +-----------+ 405 D bit=1 + + + + + 406 | | | | | 407 D bit=0 ------+----------+----------+----------+------------+----- 409 Traffic Flow 410 ===========================================================> 411 L bit ...1111111111 0000000000 11111111111 00000000000 111111111... 413 D bit ...0000010000 0000010000 00000100000 00001000000 000001000... 414 ===========================================================> 416 Figure 2: Double-Marking Methodology using L bit and D bit 418 Similar to packet delay measurement (both for Single Marking and 419 Double Marking), the method can also be used to measure the inter- 420 arrival jitter. 422 5.3. Flow Monitoring Identification 424 The Flow Monitoring Identification (FlowMonID) is required for some 425 general reasons: 427 o First, it helps to reduce the per node configuration. Otherwise, 428 each node needs to configure an access-control list (ACL) for each 429 of the monitored flows. Moreover, using a flow identifier allows 430 a flexible granularity for the flow definition. 432 o Second, it simplifies the counters handling. Hardware processing 433 of flow tuples (and ACL matching) is challenging and often incurs 434 into performance issues, especially in tunnel interfaces. 436 o Third, it eases the data export encapsulation and correlation for 437 the collectors. 439 The FlowMon identifier field is to uniquely identify a monitored flow 440 within the measurement domain. The field is set at the source node. 441 The FlowMonID can be uniformly assigned by the central controller or 442 algorithmically generated by the source node. The latter approach 443 cannot guarantee the uniqueness of FlowMonID but it may be preferred 444 for local or private network, where the conflict probability is small 445 due to the large FlowMonID space. 447 5.3.1. Uniqueness of FlowMonID 449 It is important to note that if the 20 bit FlowMonID is set 450 independently and pseudo randomly there is a chance of collision. 451 So, in some cases, FlowMonID could not be sufficient for uniqueness. 453 In general the probability of a flow identifier uniqueness correlates 454 to the amount of entropy of the inputs. For instance, using the 455 well-known birthday problem in probability theory, if the 20 bit 456 FlowMonID is set independently and pseudo randomly without any 457 additional input entropy, there is a 50% chance of collision for just 458 1206 flows. For a 32 bit identifier the 50% threshold jumps to 459 77,163 flows and so on. So, for more entropy, FlowMonID can either 460 be combined with other identifying flow information in a packet (e.g. 461 it is possible to consider the hashed 3-tuple Flow Label, Source and 462 Destination addresses) or the FlowMonID size could be increased. 464 This issue is more visible when the FlowMonID is pseudo randomly 465 generated by the source node and there needs to tag it with 466 additional flow information to allow disambiguation. While, in case 467 of a centralized controller, the controller should set FlowMonID by 468 considering these aspects and instruct the nodes properly in order to 469 guarantee its uniqueness. 471 5.4. Multipoint and Clustered Alternate Marking 473 The Alternate Marking method can also be extended to any kind of 474 multipoint to multipoint paths, and the network clustering approach 475 allows a flexible and optimized performance measurement, as described 476 in [I-D.ietf-ippm-multipoint-alt-mark]. 478 The Cluster is the smallest identifiable subnetwork of the entire 479 Network graph that still satisfies the condition that the number of 480 packets that goes in is the same that goes out. With network 481 clustering, it is possible to use the partition of the network into 482 clusters at different levels in order to perform the needed degree of 483 detail. So, for Multipoint Alternate Marking, FlowMonID can identify 484 in general a multipoint-to-multipoint flow and not only a point-to- 485 point flow. 487 5.5. Data Collection and Calculation 489 The nodes enabled to perform performance monitoring collect the value 490 of the packet counters and timestamps. There are several 491 alternatives to implement Data Collection and Calculation, but this 492 is not specified in this document. 494 6. Security Considerations 496 This document aims to apply a method to perform measurements that 497 does not directly affect Internet security nor applications that run 498 on the Internet. However, implementation of this method must be 499 mindful of security and privacy concerns. 501 There are two types of security concerns: potential harm caused by 502 the measurements and potential harm to the measurements. 504 Harm caused by the measurement: Alternate Marking implies 505 modifications on the fly to an Option Header of IPv6 packets but this 506 must be performed in a way that does not alter the quality of service 507 experienced by the packets and that preserves stability and 508 performance of routers doing the measurements. The advantage of the 509 Alternate Marking method is that the marking bits are the only 510 information that is exchanged between the network nodes. Therefore, 511 network reconnaissance through passive eavesdropping on data-plane 512 traffic does not allow attackers to gain information about the 513 network performance. Moreover, Alternate Marking should usually be 514 applied in a controlled domain and this also helps to limit the 515 problem. 517 Harm to the Measurement: Alternate Marking measurements could be 518 harmed by routers altering the marking of the packets or by an 519 attacker injecting artificial traffic. Since the measurement itself 520 may be affected by network nodes along the path intentionally 521 altering the value of the marking bits of IPv6 packets, the Alternate 522 Marking should be applied in the context of a controlled domain, 523 where the network nodes are locally administered and this type of 524 attack can be avoided. Indeed the source and destination addresses 525 are within the controlled domain and therefore it is unlikely subject 526 to hijacking of packets, because it is possible to filter external 527 packets at the domain boundaries. In addition, an attacker cannot 528 gain information about network performance from a single monitoring 529 point; it must use synchronized monitoring points at multiple points 530 on the path, because they have to do the same kind of measurement and 531 aggregation as Alternate Marking requires. 533 The privacy concerns of network measurement are limited because the 534 method only relies on information contained in the Option Header 535 without any release of user data. Although information in the Option 536 Header is metadata that can be used to compromise the privacy of 537 users, the limited marking technique seems unlikely to substantially 538 increase the existing privacy risks from header or encapsulation 539 metadata. 541 The Alternate Marking application described in this document relies 542 on an time synchronization protocol. Thus, by attacking the time 543 protocol, an attacker can potentially compromise the integrity of the 544 measurement. A detailed discussion about the threats against time 545 protocols and how to mitigate them is presented in [RFC7384]. 547 7. IANA Considerations 549 The Option Type should be assigned in IANA's "Destination Options and 550 Hop-by-Hop Options" registry. 552 This draft requests the following IPv6 Option Type assignments from 553 the Destination Options and Hop-by-Hop Options sub-registry of 554 Internet Protocol Version 6 (IPv6) Parameters 555 (https://www.iana.org/assignments/ipv6-parameters/). 557 Hex Value Binary Value Description Reference 558 act chg rest 559 ---------------------------------------------------------------- 560 TBD 00 0 tbd AltMark [This draft] 562 8. Acknowledgements 564 The authors would like to thank Bob Hinden, Ole Troan, Tom Herbert, 565 Stefano Previdi, Brian Carpenter, Eric Vyncke, Ron Bonica for the 566 precious comments and suggestions. 568 9. References 569 9.1. Normative References 571 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 572 Requirement Levels", BCP 14, RFC 2119, 573 DOI 10.17487/RFC2119, March 1997, 574 . 576 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 577 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 578 May 2017, . 580 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 581 (IPv6) Specification", STD 86, RFC 8200, 582 DOI 10.17487/RFC8200, July 2017, 583 . 585 9.2. Informative References 587 [I-D.fioccola-v6ops-ipv6-alt-mark] 588 Fioccola, G., Velde, G., Cociglio, M., and P. Muley, "IPv6 589 Performance Measurement with Alternate Marking Method", 590 draft-fioccola-v6ops-ipv6-alt-mark-01 (work in progress), 591 June 2018. 593 [I-D.ietf-ippm-multipoint-alt-mark] 594 Fioccola, G., Cociglio, M., Sapio, A., and R. Sisto, 595 "Multipoint Alternate Marking method for passive and 596 hybrid performance monitoring", draft-ietf-ippm- 597 multipoint-alt-mark-09 (work in progress), March 2020. 599 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 600 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 601 2006, . 603 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 604 "IPv6 Flow Label Specification", RFC 6437, 605 DOI 10.17487/RFC6437, November 2011, 606 . 608 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 609 of IPv6 Extension Headers", RFC 7045, 610 DOI 10.17487/RFC7045, December 2013, 611 . 613 [RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in 614 Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384, 615 October 2014, . 617 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 618 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 619 "Alternate-Marking Method for Passive and Hybrid 620 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 621 January 2018, . 623 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 624 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 625 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 626 . 628 Authors' Addresses 630 Giuseppe Fioccola 631 Huawei 632 Riesstrasse, 25 633 Munich 80992 634 Germany 636 Email: giuseppe.fioccola@huawei.com 638 Tianran Zhou 639 Huawei 640 156 Beiqing Rd. 641 Beijing 100095 642 China 644 Email: zhoutianran@huawei.com 646 Mauro Cociglio 647 Telecom Italia 648 Via Reiss Romoli, 274 649 Torino 10148 650 Italy 652 Email: mauro.cociglio@telecomitalia.it 654 Fengwei Qin 655 China Mobile 656 32 Xuanwumenxi Ave. 657 Beijing 100032 658 China 660 Email: qinfengwei@chinamobile.com 661 Ran Pang 662 China Unicom 663 9 Shouti South Rd. 664 Beijing 100089 665 China 667 Email: pangran@chinaunicom.cn